The present invention relates to a battery including a cathode, an anode, and an electrolyte, particularly to a battery including a cathode, an anode, and an electrolyte and using lithium (Li) or the like as an electrolytic reactant.
In recent years, downsizing and weight saving of portable electronic devices represented by a mobile phone, PDA (Personal Digital Assistant), and a notebook personal computer have been actively promoted. As a part thereof, improving the energy density of the battery, the driving power source for such electronic devices, in particular of the secondary battery has been strongly desired. As a secondary battery capable of providing a high energy density, the lithium ion secondary battery using a material capable of inserting and extracting lithium such as carbon materials for the anode is commercialized, and the market thereof is expanded.
Further, as a secondary battery capable of providing a high energy density, there is the lithium metal secondary battery using a lithium metal for the anode and utilizing only precipitation and dissolution reaction of the lithium metal for anode reaction. In the lithium metal secondary battery, the theoretical electrochemical equivalent of the lithium metal is large, 2054 mAh/cm3, which corresponds to 2.5 times of graphite used in the lithium ion secondary battery. Therefore, the lithium metal secondary battery is expected to be the battery capable of providing an energy density higher than of the lithium ion secondary battery. Up to this day, many researchers have made research and development on practical application of the lithium metal secondary battery (for example, refer to “Lithium Batteries,” edited by Jean-Paul Gabano, London, N.Y., Academic Press, 1983).
Further, recently, a secondary battery in which the anode capacity includes a capacity component due to insertion and extraction of lithium and a capacity component due to precipitation and dissolution of lithium, and is expressed by the sum thereof has been developed (for example, refer to International Publication No. 01/22519). In the secondary battery, a carbon material capable of inserting and extracting lithium is used for the anode, and lithium is precipitated on the surface of the carbon material in the middle of charge. According to the secondary battery, it is expected to attain a high energy density as in the lithium metal secondary battery.
In the foregoing lithium secondary batteries, traditionally, it has been considered to use a mixture of two or more solvents or to use a halogenated compound or the like for the electrolyte in order to improve battery characteristics such as cycle characteristics (for example, refer to Japanese Unexamined Patent Application Publication Nos. S62-290071 and S62-217567).
However, with the foregoing means, the effects are not exactly sufficient. In particular, in the lithium metal secondary battery, in the secondary battery in which the anode capacity includes a capacity component due to insertion and extraction of lithium and a capacity component due to precipitation and dissolution of lithium, and is expressed by the sum thereof, or in the lithium ion secondary battery in which the anode contains an anode material capable of inserting and extracting an electrode reactant and containing at least one of metal elements and metalloid elements as an element, sufficient cycle characteristics have not been obtained.